Support structure for a back part and/or a seat of a seat assembly and seat assembly comprising such a support structure

ABSTRACT

A support structure for a back part and/or a seat of a seat assembly includes a base support, a support part, and a power system. The support part is arranged on the base support to support and/or hold the respective back part and/or seat, and is attached to the base support to allow movement of the support part relative to the base support. The power system, which includes first and second spring elements and a coupling device, generates a reset force in response to (and directed opposite to) the respective movement of the support part. When the coupling device is in a first state, the second spring element generates a second reset force directed opposite to the movement of the support part. When the coupling device is in the second state, the second spring element does not generate the second reset force.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of European Patent Application No. EP 10405014, filed on Jan. 22, 2010, the entirety of which is hereby incorporated by reference.

BACKGROUND

1. Field of Invention

The invention relates to a support structure for a back part and/or a seat of a seat assembly and to a seat assembly comprising such a support structure.

2. Related Art

For the most part, seat assemblies, for example chairs, have a modular structure: in addition to a seat and a back part, if necessary, which can comprise a backrest, for example, they normally also comprise a support structure for the respective back part and/or the respective seat, wherein it is the object of the support structure to hold the seat and the back part, if necessary, in a certain position and to accommodate a load, which can be transferred onto the seat or the back part, respectively, by a person sitting on the seat assembly, for example, and to hold the seat and the back part, if necessary, in a stable position in each case in response to the impact of the respective load.

Oftentimes, seat assemblies are not embodied so as to be rigid. Oftentimes, the respective support structure is constructed such that even though the support structure can be positioned in the room in a stationary manner, the spatial position of the respective back part and/or of the respective seat can be changed relative to the support structure. This provides for the possibility, for example, that the spatial arrangement of the back part and/or of the seat can be adapted to the respective posture of a person, who sits on the respective seat assembly and who constantly changes his posture, on the one hand, or to achieve, for example, that the same seat assembly can be adjusted to different requirements of different persons, who can differ with regard to their height or weight or with regard to their preferred posture when sitting. For this purpose, a conventional support structure of a seat assembly usually comprises a base support, which can be positioned in a stationary manner in the room, and at least one support part, which is arranged on the base support and which is attached to the base support such that a movement of the support part can be carried out relative to the base support. The purpose of said support part is to hold the back part and/or the seat in a position, which is a function of the relative position of the support part with respect to the base support. The back part or the seat, respectively, must thereby not be attached directly to the support part: the back part or the seat, respectively, can in each case be connected to said support part or can be coupled to the support part via one or a plurality of other components.

A support structure of the afore-mentioned type can also be equipped with a power system for generating at least one reset force, which is generated in response to the respective movement of the support part and which is directed opposite to this movement. For example, such a power system can comprise one or a plurality of spring elements, which are in each case coupled to the base support and the support part such that the spring element generates a reset force, which is directed opposite to the respective movement of the support part in response to the respective movement. Such a power system ensures a flexible arrangement of the back part or of the seat, respectively, such that the respective back part and/or the respective seat are deflected out of a predetermined position of equilibrium, if necessary, in response to the impact of a force, wherein the support part is at the same time deflected out of a predetermined position of equilibrium and a reset force, which counteracts the deflection of the support part, is generated. As a rule, the respective reset force is thereby greater, the further the support part is deflected out of the original position of equilibrium. Due to the fact that the power system generates a reset force, which is directed opposite to the respective movement of the support part, the support part can subsequently assume a new position of equilibrium as soon as all of the forces acting on the support part compensate one another. In so doing, the back part or the seat, respectively, can in each case be held in a position of equilibrium, which is a function of the respective stress of the back part or of the seat, respectively. The latter ensures a high seating comfort, the more so as the rear part and/or the seat can in each case be adapted to the current posture of a person sitting on the seat assembly and the respective reset force created by the power system in each case acts as a support for the person, who is sitting down.

To even further improve the seating comfort, which is ensured by a power system of the afore-mentioned type, such a power system can be designed such that the size of the reset force, which the power system generates in response to a certain deflection of the support part out of a predetermined position of equilibrium, can be varied to a certain extent and can be adjusted, as needed. The latter allows for the power system to be adapted to different requirements. As a rule, an adjustment of the power system in which the power system generates a relatively large reset force in response to a predetermined deflection of the support part (“hard” adjustment of the power system), is appropriate in the case of tall or heavy persons, respectively, for example, while in the case of short or light persons, respectively, an adjustment of the power system in which the power system generates a relatively small reset force in response to a predetermined deflection (“soft” adjustment of the power system) would be more suitable.

A seat assembly, which comprises a changeable power system of the afore-mentioned type, is known from EP 1486142 A1. This seat assembly, a chair, encompasses a support structure in combination with a power system of the afore-mentioned type. In this case, the power system comprises an elastomer torsion spring element, which serves the purpose of generating a reset torque, which counteracts a pivoting motion of a support for a seat (referred to hereinbelow as “seat support”, if applicable) about an axis of rotation. The elastomer torsion spring element includes an inner housing and an outer housing, wherein an elastomer body is integrated in a space between the inner housing and the outer housing. On its outer side, the inner housing encompasses a contact surface, on which the elastomer body is in contact with the inner housing and on its inner side, the outer housing encompasses contact surface, on which the elastomer body is in contact with the outer housing. The elastomer body is thereby fixedly connected to the respective contact surface of the inner housing and of the respective contact surface of the outer housing, so that the elastomer body can neither slip on the contact surface of the inner housing nor on the contact surface of the outer housing relative to the inner housing or to the outer housing. In the instant case, the outer housing and the inner housing are embodied in a cylindrical manner and are oriented coaxially to one another. The outer housing is held on a support structure of the chair, while the inner housing sits on a shaft in a torque proof manner, with said shaft being capable of rotating about its longitudinal axis. A seat of the chair is coupled to the shaft such that the shaft is rotated about its longitudinal axis and the seat is pivoted out of a predetermined basic position in the event that the seat is loaded by the weight of a person. Due to the rotation of the shaft, the inner housing is rotated about its longitudinal direction and is thereby twisted relative to the outer housing with the effect that the elastomer torsion spring element generates a reset torque, which acts on the shaft or on the seat, respectively, and which counteracts the rotation of the shaft or the pivoting motion of the seat, respectively, and which increases as the angle of rotation increases. In the case of the torsion spring element, the size of the minimal torque acting on the shaft when the seat is pivoted out of the mentioned basic position (referred to hereinbelow as “minimum reset torque”) can be changed. For this purpose, the outer housing can be rotated about its longitudinal axis by means of a rotating mechanism, which is arranged on the support structure of the chair, and can thus be rotated about the longitudinal axis of the shaft, wherein the outer housing is twisted relative to the support structure of the chair and relative to the inner housing or to the shaft, respectively. The elastomer torsion spring element is prestressed by means of the twisting of the outer housing relative to the inner housing, wherein the angle or rotation, about which the outer housing is twisted relative to the inner housing when the seat is located in the basic position, determines the size of the “minimum reset torque”.

The power system of the afore-mentioned seat assembly has different disadvantages. The mentioned elastomer torsion spring element has the disadvantage that the reset torque, which is generated in response to a rotation of the mentioned shaft about a certain angle of rotation, shows a relatively low increase as function of the respective angle of rotation, in particular when the elastomer torsion spring element is not or only slightly prestressed. According thereto, the outer housing of the elastomer torsion spring element must be twisted about a relatively large angle of rotation relative to the inner housing and the elastomer body of the elastomer torsion spring element must be prestressed to a relatively large extent when a large minimum reset torque is to be adjusted, so as to be able to provide an adequate seating comfort to persons with a heavy weight, e.g. In response to the twisting of the outer housing of the elastomer torsion spring element relative to the inner housing, a relatively large force must be applied when the elastomer body is to be prestressed to a large extent so as to achieve the highest possible reset torque. It is thus time-consuming and laborious to vary the minimum reset torque by manually twisting the outer housing relative to the inner housing across a large area. The reset torque generated by the elastomer torsion spring element further increases in a highly non-linear manner (progressively) as a function of the angle of rotation of the shaft when the shaft is to be rotated about an angle of rotation in the range of from 0 to approx. 70°, for example. In the area of the upper end of the mentioned area of the angle of rotation, the elastomer body is already prestressed to such an extent that damages to the elastomer body must be expected in response to a further increase of the angle of rotation. The minimum reset torque of the elastomer torsion spring element can thus only be increased up to a certain upper limit. The resilience of the power system is thus limited.

SUMMARY

It is an object to avoid the abovementioned disadvantages and to create a support structure or a seat assembly, respectively, comprising a power system, which makes it possible to be able to change the reset force, which is in each case generated by the power system, across the largest possible range in a simple and comfortable manner, so that the power system can be adapted to the requirements of different persons with large differences with regard to their weight in a simple and comfortable manner.

This and other objects are solved by means of a support structure for a back part and/or a seat of a seat assembly, and by means of a seat assembly including such a support structure.

According to an embodiment of the invention, the support structure comprises a base support, at least one support part, which is arranged on the base support, for supporting and/or holding the respective back part and/or the respective seat, with said support part being attached to the base support such that a movement of the support part relative to the base support can be carried out, and a power system for generating at least one reset force, which is generated in response to the respective movement of the support part and which is directed opposite to this movement. The power system thereby comprises at least a first spring element, which is coupled to the base support and to the support part such that, in response to the respective movement of the support part, the first spring element generates a first reset force, which is directed opposite to the movement of the support part.

The support part is thereby embodied to hold the respective back part and/or the respective seat of the respective seat assembly in a position, which is a function of the relative position of the support part with reference to the base support. The back part or the seat, respectively, must thereby not be attached directly to the support part: the back part or the seat, respectively, can in each case be connected to the mentioned support part or coupled to the support part via one or a plurality of other components.

According to an embodiment of the invention, the power system additionally comprises at least a second spring element and at least one coupling device for coupling the respective second spring element to the base support and/or to the support part, with said coupling device being capable of being brought either into a first or into a second state, wherein

-   -   in the event that the coupling device is brought into the first         state, the respective second spring element is coupled to the         base support and to the support part such that the respective         second spring element, in response to the respective movement of         the support part, generates a second reset force, which is         directed opposite to the respective movement of the support part         and     -   in the event that the coupling device is brought into the second         state, the respective second spring element is not coupled to         the base support and/or to the support part, so that the         respective second spring element does not generate a reset         force, which is directed opposite to the respective movement.

Accordingly, the power system of the support structure according to an embodiment of the invention comprises different groups of spring elements comprising different functions: one or a plurality of “first” spring elements and one or a plurality of “second” spring elements.

The respective first spring element is thereby in each case coupled to the base support and to the support part and generates a (“first”) reset force, which in each case acts on the support part, when the support part is moved relative to the base support. In the event that the power system comprises a plurality of first spring elements of this type, the totality of all of the first spring elements generates a reset force, which acts on the support part and which corresponds to the sum of the reset forces, which are generated by the respective first spring elements.

However, the respective second spring element can either be coupled to the base support as well as to the support part—as a function on the respective state of the coupling device—or (in each case as a function of the respective realization of the coupling device) it can be decoupled at least from the base support or at least from the support part or from the base support as well as from the support part. The respective second spring element only generates a (“second”) reset force, which acts on the support part—in addition to the reset force, which is generated by the respective first spring elements—when the support part is moved relative to the base support when the coupling device is in a state, in which the respective second spring element is coupled to the base support as well as to the support part. In the other state of the coupling device, the respective second spring element cannot generate a reset force, which acts on the support part—due to the decoupling from the base support and/or from the support part.

In the event that the power system comprises a plurality of second spring elements of this type, the totality of all second spring elements generates a reset force, which acts on the support part and which corresponds to the sum of all reset forces being generated by those second spring elements, which are currently coupled to the base support as well as to the support part by means of the respective coupling devices.

Accordingly, a reset force, which corresponds to the sum of all of the (“first” and “second”) reset forces generated by the respective first and second spring elements, acts on the support part in each case.

According to an embodiment of the invention, the reset force acting on the support part can be changed by changing the state of the respective coupling device, wherein the number of those second spring elements, which are currently coupled to the base support as well as to the support part, is changed in each case.

The reset force acting on the support part (in response to a predetermined deflection of the support part out of a basic position), can thereby be varied in a range, the size of which is substantially a function of the number of the respective second spring elements and of the respective characteristics of the respective second spring elements. Due to the fact that the number of the respective second spring elements can on principle be chosen randomly, the invention allows for the variation of the reset force, which acts on the support part, in any range, by means of suitably selecting the number of the second spring elements and by suitably selecting the characteristics of the respective spring elements. The characteristics of the respective spring elements can thereby be chosen such that none of the spring elements can be overloaded. The support structure according to an embodiment of the invention can thus in each case be designed such that the support structure can be adapted to the requirements of different persons having large differences with regard to their weight. In the event that the support structure is to be adjusted to a person having a relatively small weight, the respective coupling devices can in each case be brought into a state, for example, in which none of the respective second spring elements is coupled to the base support as well as to the support part. In this case, only the respective first spring elements contribute to the reset force, which acts on the support part. In the event, however, that the support structure is to be adjusted to a person having a relatively large weight, the respective coupling devices can be brought into a state, for example, in which the respective second spring elements are coupled to the base support as well as to the support part. In this case, all of the first and second spring elements contribute to the reset force, which acts on the support part.

Advantageously, there are no limitations with reference to the selection of the respective spring elements: on principle, any type of spring elements can be used to realize the support structure according to the invention, e.g. spring elements, which comprise an elastically deformable body, or pneumatic or hydraulic spring elements, or spring elements, which can be loaded by means of a torsion or a pressure or a tension, or other spring elements.

The respective coupling device can be realized in many ways, for example with mechanical means, electromechanical, magnetic, pneumatic, hydraulic or other means.

Advantageously, the coupling device can be realized such that movements, which must be carried out opposite to a force, which is generated by the respective second spring element, are not necessary in response to the coupling of the respective second spring element to the base support or to the support part, respectively, or in response to the decoupling of the respective second spring element from the base support or from the support part, respectively. As a rule, the respective coupling device can thus be brought from one of the respective states into a different state quickly, with a small expenditure of force and thus comfortably for a user.

An embodiment of the support structure according to the invention comprises a control device for impacting the respective state of the respective coupling device such that the respective coupling device can either be brought into the first or the second state. Such a control device makes it possible for a user to comfortably bring the coupling device into the different states, without having to touch the coupling device or the respective spring element, which is to be coupled to the base support or the support part, respectively, by means of the coupling device. This is so because, as a rule, the coupling device or the respective spring element is not easily accessible to a user. The control device makes it possible for a user to control the respective coupling device in a simple and comfortable manner, for example when sitting on the respective seat assembly. Such a control device is advantageous, in particular, when a plurality of coupling devices are available and must be controlled independent on one another. Such a control device can be realized in many different ways, for example by means of mechanical, electromechanical, electrical, pneumatic, hydraulic or other means (in each case depending on the construction and the function of the respective coupling devices).

An embodiment of the support structure according to the invention comprises a plurality of second spring elements and a plurality of coupling devices, wherein two different coupling devices can in each case be brought into the first or the second state independent on one another. In this case, a plurality of second spring elements can be coupled to the base support or to the support part, respectively, independent on one another and can be decoupled from the base support and/or from the support part. In an alternative of this embodiment, the support structure can be embodied such that the respective second spring elements a) can in each case be brought into a state, in which none of the second spring elements is coupled to the base support and to the support part or b) can in each case be brought into a state, in which one of the second spring elements is coupled to the base support and to the support part, or c) can in each case be brought into a state, in which a plurality of the second spring elements are coupled to the base support and to the support part. Based on a state, in which none of the second spring elements is coupled to the base support as well as to the support part, this embodiments makes it possible to successively increase the number of the second spring elements, which are coupled to the base support and to the support part, by impacting the respective coupling device and to thus increase the reset force, which can be generated by means of the power system, step by step in a plurality of steps. This embodiment has the advantage that the power system can be adapted to the respective weight of different persons in a particularly fine and accurate manner, namely for a range of weights, which is greater, the greater the number of the second spring elements.

As a rule, the respective spring elements are constructed such that the generation of a reset force is connected to a change of the extension of the respective spring element in at least one direction.

An embodiment of the support structure is accordingly characterized in that the respective second spring element encompasses a first section and a second section, with said sections being capable of being moved relative to one another for generating the respective reset force. The coupling device further comprises:

-   -   (i) a first holding means for holding the first section of the         respective second spring element, with said first holding means         being connected to the base support and being embodied to         interact with the first section of the respective second spring         element such that this first section of the respective second         spring element is held in a predetermined position relative to         the base support, in the event that the coupling device is         brought into the first state and     -   (ii) a second holding means for holding the second section of         the respective second spring element, with said second holding         means being connected to the support part and being embodied to         interact with the second section of the respective second spring         element such that this second section of the respective second         spring element is held in a predetermined position relative to         the support part in the event that the coupling device is         brought into the first state.

This embodiment has the advantage that the coupling device can be realized with simple means (based on holding means). A movement of the support part relative to the base support in each case acts on that second spring element, the first section of which is held by the first holding means and the second section of which is held by the second holding means, such that the first section of this second spring element is moved in response to a movement of the support part relative to the second section of the second spring element, so that the second spring element inevitably generates a reset force, which acts on the support part.

An advantageous alternative of the aforementioned embodiment is designed such that the first holding means of the respective coupling device is embodied to hold the first section of the respective second spring element so as to be capable of being detached and—in the event that the coupling device is brought into the second state—is brought into a state, in which the first section of the respective second spring element is detached from the respective first holding means in response to the respective movement of the support part, and/or that the second holding means of the respective coupling device is embodied for holding the second section of the respective second spring element so as to be capable of being detached and—in the event that the coupling device is brought into the second state—is brought into a state, in which the second section of the respective second spring element is detached from the respective second holding means in response to the respective movement of the support part. To achieve that the respective second spring element is not coupled to the base support and to the support part and to accordingly not generate a reset force, the coupling device must be equipped such that the second spring element is detached from the first holding means and/or from the second holding means. It is thus not necessary for the first holding means as well as the second holding means to be embodied as means for detachably holding, so as to provide for a decoupling of the second spring element from the base support or from the support part, respectively. When the second holding means is designed such, for example, that it can hold the second section of the second spring element so as to be capable of being detached, the first holding means can then also be embodied such that it establishes a fixed, rigid connection, if necessary, between the second section of the second spring element and the base support.

If, on the other hand, the first holding means is designed such that it can hold the first section of the second spring element so as to be capable of being detached, the second holding means can then also be embodied such that it established a fixed, rigid connection, if necessary, between the first second of the second spring element and the support part.

In a further development of the afore-mentioned embodiment of the support structure, the first holding means can be a movable part, for example, which can be brought into at least two different positions, wherein the first holding means, in one of these positions, is in contact with the first section of the respective second spring element such that this first section is held in the predetermined position relative to the base support, and is separated from the first section of the respective second spring element in the other one of these positions. Accordingly, the second holding means can be a movable part, which can be brought into at least two different positions, wherein the second holding means, in one of these positions, is in contact with the second section of the respective second spring element such that this second section is held in the predetermined position relative to the support part and is separated from the second section of the respective second spring element in the other one of these positions.

The support structure can comprise an actuating means for moving the respective holding means from one of these positions into another one of the positions. The actuating means makes it possible for the user to move the respective holding means in a simple manner and to thus impact the respective state of the coupling device. In the event that the support structure comprises a plurality of second spring elements and accordingly a plurality of first and second holding means for holding the respective second spring elements, it is advantageous to design a single actuating means such that all of the movable holding means can be moved with this actuating means independent on one another.

The actuating means can be a rotatable cam shaft, for example, on which at least one cam, which is assigned to the respective holding means, is arranged such that the respective holding means can be moved by means of the respective assigned cam in response to a rotation of the cam shaft.

In the event that the support structure comprises a plurality of second spring elements and accordingly a plurality of first and second holding means for holding the respective second spring elements, the cam shaft can be embodied such that a plurality of cams are embodied on the cam shaft such that the respective second spring elements can in each case be coupled successively to the base support as well as to the support part in response to a rotation of the cam shaft beyond a predetermined range of the angle range of rotation. In this case, the number of the second spring elements, which are in each case coupled to the base support as well as to the support part and which accordingly generate a reset force in response to a movement of the support part, can be increased successively by rotating the cam shaft.

An elastomer torsion spring element, which comprises an inner housing, an outer housing surrounding the inner housing and an elastomer body, which is arranged in a space between the inner housing and the outer housing, for example, can be used as first and/or second spring element of the respective power system of the respective support structures. Said inner housing encompasses at least one contact surface, at which the elastomer body is in contact with the inner housing. Said outer housing encompasses at least one contact surface, at which the elastomer body is in contact with the outer housing, wherein the elastomer body is fixedly connected to the contact surface of the inner housing and to the contact surface of the outer housing and wherein the inner housing and/or the outer housing is arranged so as to be capable of being rotated about an axis of rotation.

In the event that the respective first spring element is embodied in the form of the afore-mentioned elastomer torsion spring element, this elastomer torsion spring element can then be coupled to the base support and to the support part such that the respective movement of the support part causes a rotation of the inner housing and/or of the outer housing about the axis of rotation such that the inner housing is moved relative to the outer housing in response to the rotation and a deformation of the elastomer body is thereby generated, so that the elastomer body generates a reset torque between the outer housing and the inner housing, which is directed opposite to the rotation. Accordingly, in the event that the respective second spring element is embodied in the form of the above-mentioned elastomer torsion spring element, this elastomer torsion spring element can be coupled to the base support and to the support part by means of the respective coupling device such that the respective movement of the support part causes a rotation of the inner housing and/or of the outer housing about the axis of rotation such that the inner housing is moved relative to the outer housing in response to the rotation and a deformation of the elastomer body is thereby generated, so that the elastomer body generates a reset torque between the outer housing and the inner housing, which is directed opposite to the rotation. The reset torque is accompanied by a reset force, which acts on the support part, due to the mentioned coupling between the outer housing or the inner housing, respectively, and the base support or the support part, respectively.

Elastomer torsion spring elements of the aforementioned type have the advantage that they make it possible to realize the respective power system in a particularly compact (space-saving) manner and that they provide for a coupling of the respective spring element to the base support and to the support part, which can be realized by means of particularly simple means. This applies in particular when the respective support part is attached to a bearing shaft, which is supported on the base support such that the support part can be pivoted about a pivot axis. In this case, the respective elastomer torsion spring element can be coupled to the base support and to the support part, for example, such that the outer housing is rigidly connected to the base support and that the inner housing is rigidly connected to the support part or to the bearing shaft. In the alternative, the inner housing can be rigidly connected to the base support and the outer housing can be rigidly connected to the support part or to the bearing shaft. The inner housing of the respective elastomer torsion spring element can thereby be realized in the form of a ring-shaped structure, which can be attached onto the bearing shaft such that the inner housing surrounds the bearing shaft in a ring-shaped manner. In the alternative, the bearing shaft can be realized in the form of a pipe and the elastomer torsion spring element can be installed into the pipe.

Advantageously, the respective elastomer torsion spring element of the afore-mentioned type can be formed such that the contact surface of the inner housing encompasses a non-circular cross section in a sectional plane, which is vertical to the axis of rotation and/or that the contact surface of the outer housing encompasses a non-circular cross section in a sectional plane, which is vertical to the axis of rotation. The mentioned cross sections of the inner housing or of the outer housing, respectively, can be embodied so as to be angular, for example, and can encompass the form of a square or of a rectangle, for example. This has the advantage that the reset torque, which generates such an elastomer torsion spring element when the outer housing is twisted about a certain angle of rotation relative to the inner housing, varies to a relatively high degree with the angle of rotation. Such an elastomer torsion spring element thus makes it possible to generate a relatively large reset torque in response to a predetermined angle of rotation (as compared to the elastomer torsion spring element known from EP 1486142 A1, the inner housing and the outer housing of which in each case encompass contact surfaces, which adjoin the respective elastomer body and the cross section of which encompasses the shape of a circle in a sectional plane, which is vertical to the axis of rotation). The reset torque furthermore displays a linear rise as function of the angle of rotation across a relatively large area of the angle of rotation.

In an alternative of the above-mentioned elastomer torsion spring elements, at least one holding element can be arranged in each case on the respective elastomer torsion spring element, with said holding element being designed

-   -   to hold the inner housing of the elastomer torsion spring         element in a predetermined basic position relative to the outer         housing of the elastomer torsion spring element, with the         elastomer body encompassing a predetermine elastic deformation         in said basic position and generating a reset torque, which         equals a predetermined minimum value, between the outer housing         and the inner housing and     -   to release a rotation of the inner housing relative to the outer         housing about an angle of rotation about the axis of rotation in         a direction of rotation, in which the reset torque increases         with an increasing angle of rotation.

Accordingly, the elastomer body of this elastomer torsion spring element is prestressed when the inner housing of the elastomer torsion spring element is in the respective basic position. Such an elastomer torsion spring is thus able, in response to any small deflection of the support part out of a basic position, to generate a reset force, which acts on the support part and which is always greater than a minimum value (greater than 0). Accordingly, a reset force can be generated, which acts on the support part and which is sufficient to support a relatively heavy person even if the support part is in a basic position. In the case of a power system comprising a plurality of spring elements, different spring elements can also be prestressed to varying degrees, so that they generate different-sized reset forces.

The holding element of the afore-mentioned type can be realized in different ways.

In one embodiment, the holding element includes at least one clamping element, which either encompasses a first section, which is fixedly engaged with the inner housing, and which encompasses a second section, which strikes against a section of the outer housing—when the inner housing is in the predetermined basic position relative to the outer housing—and releases a rotation of the inner housing and of the outer housing in relation to one another about the axis of rotation in that direction of rotation, in which the reset torque increases. Advantageously, this embodiment provides the opportunity for a plurality of elastomer torsion spring elements, the inner housings of which are connected to one another in a torsionally rigid manner, to be prestressed together in a single operating step. This simplifies the assembly of a power system comprising a plurality of elastomer torsion spring elements, which are to be prestressed in a predetermined basic position. In the alternative, the clamping element can also encompass a first section, which is fixedly engaged with the outer housing and can encompass a second section, which strikes against a section of the inner housing—when the inner housing is in the predetermined basic position relative to the outer housing—and releases a rotation of the inner housing and of the outer housing in relation to one another about the axis of rotation in that direction of rotation, in which the reset torque increases.

In a further alternative, the inner housing comprises a recess. The first section of the clamping element is furthermore inserted into this recess in the inner housing in a torsionally rigid manner and the second section of the clamping element strikes against a section of the outer housing when the inner housing is in the predetermined basic position relative to the outer housing. This alternative makes it possible for the elastomer body of an individual elastomer torsion spring element of the afore-mentioned type to be prestressed initially in that the outer housing is twisted relative to the inner housing. After the clamping element has been inserted into the recess in the inner housing as mentioned, the outer housing is held in a basic position such that the prestress of the elastomer body is retained. The elastomer torsion spring element, which is prestressed in such a manner, has the advantage that, together with the clamping element, it forms a modular unit, which (in the prestressed state) can be transported as a whole and can be assembled into a support structure according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details of the invention and in particular exemplary embodiments of the support structure according to the invention will be specified below in connection with a seat assembly by means of the enclosed drawings.

FIG. 1 shows a part of a seat assembly in the form of an office chair in a first perspective illustration, comprising a support structure according to an embodiment of the invention for a back part and a seat of the seat assembly;

FIG. 2 shows the support structure according to FIG. 1, comprising a base support and a support part, which can be moved relative to the base support, for the back part and the seat in a perspective illustration;

FIGS. 3A, 3B show in each case the support structure according to FIG. 2 in a side view, wherein FIG. 3A shows the support structure in a state, in which the support part is in a basic position and FIG. 3B shows the support structure in a state, in which the support part is deflected out of the basic position;

FIGS. 4A, 4B show a view of the support structure according to FIG. 2 in a perspective illustration, wherein the support part and other components are removed, so as to provide for a view onto a power system of the support structure, including different spring elements in the form of elastomer torsion spring elements and onto coupling devices;

FIGS. 5A-5C show a detailed view of the support structure according to FIGS. 4A and 4B in a perspective illustration, wherein the spring elements and the coupling devices of the power system are shown in different states;

FIGS. 6A, 6B show a further detailed view of the power system according to FIGS. 5A-5C in a schematic detailed illustration, wherein the coupling devices are shown in different states;

FIGS. 7A, 7B show an exemplary embodiment of an elastomer torsion spring element in a cross section (FIG. 7A) and this elastomer torsion spring element in combination with a holding element, which holds the elastomer torsion spring element in a prestressed state, in a perspective illustration (FIG. 7B);

FIGS. 8A-8C show an illustration of a power system comprising elastomer torsion spring elements and holding elements, which hold the respective elastomer torsion spring elements in a prestressed state, wherein the respective holding elements form a different embodiment, as compared to the holding element according to FIG. 7B;

FIGS. 9A-9E show a device for producing the power system illustrated in FIGS. 8A-8C; and

FIGS. 10A, 10B show an alternative for a support of the support part on the base support of the support structure.

DETAILED DESCRIPTION

FIG. 1 shows an exemplary embodiment of a seat assembly in the form of a chair 10. The chair 10 is embodied as an office swivel chair. It comprises a support column 12, a back part 20, a seat 24 and a support structure 13 according to an embodiment of the invention for the back part 20 and for the seat 24. The support structure 13 holds the back part 20 and the seat 24 in a basic position in each case, provided that no load acts on the back part 20 or on the seat 24, respectively, and makes it possible for the back part 20 or the seat 24, respectively, to be able to be deflected out of the respective basic position, provided that a load acts on the back part or on the seat 24, respectively. In the illustration according to FIG. 1, the back part 20 or the seat 24, respectively, are unloaded and are thus in the respective basic position. In this basic position, the back part 22 is oriented in a substantially vertical manner and the seat 24 is oriented in a substantially horizontal manner.

As is suggested in FIG. 1, the support structure comprises a base support 14 (see FIG. 2), among others, which is arranged on an upper end of the support column 12 (if applicable so as to be rotatable about a vertical axis and being height-adjustable) in the instant example, and a support part 16. One end of this support part 16 is rigidly connected to a bearing shaft 18, which is supported on the base support 14 such that it can be rotated about its longitudinal direction. Accordingly, the support part 16 is arranged so as to be rotatable together with the bearing shaft 18 and thus on the base support 14 in a pivotable manner.

The base support 14 furthermore serves as a housing for accommodating mechanical elements, which will be described below, in particular in context with FIGS. 2-10.

The back part 20 comprises a backrest 22 and a connecting piece 21, which is embodied as an angle profile, wherein the backrest 22 is attached to a journal of this angle profile and the other journal of this angle profile serves to attach the back part 20 to the support part 16. As is suggested in FIGS. 1 and 2, the support part 16 on the end, which is detached from the bearing shaft 18, encompasses a channel comprising an opening adapted to the outer contour of the connecting piece 21. The end of the connecting piece 21, which is spaced apart from the backrest 22, can be inserted into this channel and can subsequently be brought alongside this channel into a position relative to the support part 16, in which the connecting piece 21 (comprising means, which are not illustrated in the figures) can be fixed to the support part 16. Fixed to the support part 16 in such a manner (as is illustrated in FIG. 1), the back part 20 is accordingly rigidly coupled to the bearing shaft 18 via the support part 16 and is thus arranged on the base support 14 in a pivotable manner.

The seat 24 is located on a seat support 28, which can be pivoted about a pivot axis in the instant case. The seat support 28 is attached to the support part 16 (as is suggested in FIG. 3A). The seat support 28 is thus supported on the support part 16 at least in a partial area. Another partial area of the seat support 28 can be supported on the base support 14.

The afore-described arrangement of the support part 16, of the back part 20 and of the seat support 28 on the base support 14 makes it possible for a person sitting on the chair 10 to be able to lean back with the backrest 22 and for the seat support 28 and thus the seat surface 24 to be capable of being pivoted at the same time synchronous to this.

To make it possible for the back part 20 and the seat 24 to be able to assume a stable position even if the back part 20 and the seat 24 are moved relative to the basic position illustrated in FIG. 1 with reference to the base support 14, the support structure 13 additionally comprises a power system (not illustrated in FIG. 1), which generates a reset force or a reset torque, respectively. Said reset force acts on the support part 16 or between the support part 16 and the base support 14 and counteracts a movement of the support part 16 relative to the basic position illustrated in FIG. 1. This power system will be specified below in context with FIGS. 2-10.

In the case of the support structure 13, the support part 16 accordingly supports the back part 20 and the seat 24 and keeps the back part 20 and the seat 24 in a position, which is a function of the relative position of the support part 16 with reference to the base support 14.

FIG. 2 shows, in a perspective illustration, the support structure 13 according to FIG. 1 including the base support 14 and the support part 16 and the seat support 28, wherein the back part 20, backrest 22 and the seat 24 are removed and are accordingly not illustrated in FIG. 2. As is suggested in FIG. 2, the bearing shaft 18 is connected in a positive fit to the support part 16 in a torsionally rigid manner via a connecting piece 26, which is attached to the support part 16. The seat support 28, to which in turn the seat 24 illustrated in FIG. 1 can be attached, is arranged above the base support 14. In the instant example, the support part 16 assumes the basic position and can, based on this basic position, be pivoted clockwise (based on the perspective illustrated in FIG. 2) about the longitudinal direction of the bearing shaft 18. The seat support 28 can follow via the mechanical coupling of the respective pivoting motion of the support part 16, which is described in combination with FIG. 1. The base support 14 is embodied in a housing-type manner and surrounds a power system 30, for example, for generating a reset force or a reset torque, respectively. Said reset force acts on the support part 16 or said reset torque acts between the support part 16 and the base support 14, respectively, and is oriented opposite to a movement of the support part 16 relative to the base support 14.

FIGS. 3A and 3B show in each case the support structure 13 illustrated in FIG. 2 in a side view, wherein the base support 14 assumes in each case the same position in the room in FIG. 3A as well as in FIG. 3B. FIG. 3A shows the support structure 13 in a state, in which the support part 16 is in the basic position. FIG. 3B shows the support structure 13 in a state, in which the support part 16 is deflected out of the basic position, that is, it is rotated or pivoted clockwise, respectively, relative to the basic position.

The state illustrated in FIG. 3B is reached as soon as a person sitting on the chair 10 leans back against the backrest 22 (not shown in FIG. 3B) and thereby exerts a force onto the backrest 22 and thus onto the support part 16, so that the backrest 22 and thus the support part 16 carries out a pivoting motion. Following the pivoting motion of the support part 16, the seat support 28 is also moved relative to the base support 14 in the situation according to FIG. 3B (as compared to the situation according to FIG. 3A). The seat 24 illustrated in FIG. 1 is thus also moved synchronous to the backrest 22 under the conditions as mentioned.

FIGS. 4A and 4B show the support structure 13, which is illustrated in FIG. 2. To make details of the base support 14 and of the power system 30 to be more visible, the support part 16 and the seat support 28 are not illustrated in FIGS. 4A and 4B.

The power system 30 according to FIGS. 4A and 4B comprises a plurality of spring elements for generating a reset force: a “first” spring element 32 and three “second” spring elements 33′, 33″ and 33″′ in the instant example. The spring elements 32, 33′, 33″ and 33″′ are in each case embodied in the form of an elastomer torsion spring element, the structure and mode of operation of which will be described in more detail below, in particular in context with FIG. 7A.

In context with the facts illustrated in FIGS. 4A and 4B, it is only relevant initially that the first spring element 32 and the second spring elements 33′, 33″ and 33″′ in each case comprise an inner housing 43, an outer housing 44 surrounding the inner housing 43 and an elastomer body 46. The elastomer body 46 is arranged in a space between the inner housing 43 and the outer housing 44, as is illustrated in FIG. 7A. The elastomer body 46 is fixedly connected to the inner housing 43 on the one side as well as to the outer housing 44. The elastomer body 46 is deformed elastically in the event that the inner housing 43 is moved relative to the outer housing 44 and then generates a reset force between the inner housing 43 and the outer housing 44, which counteracts this movement. A reset torque is accordingly generated between the inner housing 43 and the outer housing 44 in the event that the inner housing 43 is twisted relative to the outer housing 44.

The inner housing 43 of each of the spring elements 32, 33′, 33″, and 33″′ encompasses a continuous channel, the cross section of which is embodied such that the bearing shaft 18 can be guided through this channel and each of the spring elements 32, 33′, 33″ and 33″′ can be attached to the bearing shaft 18 such that the respective inner housing 43 of each of the spring elements 32, 33′, 33″ and 33″′ is connected to the bearing shaft 18 in a positive fit and sits on the bearing shaft 18 such that the respective inner housing 43 is connected to the bearing shaft 18 in a torsionally rigid manner.

As is suggested in FIGS. 4A and 4B, the first spring element 32 and the second spring elements 33′, 33″ and 33″′ are attached to the bearing shaft 18 such that they sit next to one another on the bearing shaft 18 in the above-mentioned order.

The first spring element 32 of the power system 30 is coupled to the base support 14 as well as to the support part 16 in the following manner: a first section of the first spring element 32, that is the inner housing 43 of the first spring element 32, is—as already specified—connected to the bearing shaft 18 in a torsionally rigid manner and is thus rigidly coupled to the bearing shaft 18 and thus also to the support part 16. The inner housing 43 is rotated about the axis of rotation of the bearing shaft 18 in response to a pivoting motion of the support part 16. Furthermore, a second section of the first spring element 32, the outer housing 44 of the first spring element 32, is rigidly connected to the base support 14 (which cannot be seen from FIGS. 4A and 4B, but which can be identified from the illustration of the power system 30 in FIG. 5B). In response to a pivoting motion of the support part 16, the bearing shaft 18 and the inner housing 43 of the first spring element 32 are thus together rotated about the axis of rotation (longitudinal axis) of the bearing shaft 18, while the outer housing 44 remains positioned in a stationary manner with reference to the base support 14. Accordingly, the inner housing 43 and the outer housing 44 of the first spring element 32 are rotated relative to one another in response to a pivoting motion of the support part 16. Accordingly, the elastomer body 46 of the first spring element 32 is deformed elastically, so that the first spring element 32 generates a reset torque, which acts on the bearing shaft 18 or on the support part 16, respectively, and which counteracts the pivoting motion of the support part 16.

According to an embodiment of the invention, the power system 30 provides the opportunity to bring the second spring elements 33′, 33″ and 33″′ in each case into a state (referred to hereinbelow as “coupled state”), in which the respective spring element 33′, 33″ or 33″′ is coupled to the base support 14 and to the support part 16 and to further bring it into another state (referred to hereinbelow as “uncoupled state”), in which the respective second spring element 33′, 33″ or 33″′ is not coupled to the base support 14 and/or to the support part 16.

For this purpose, the power system 30 comprises a coupling mechanism 34 for coupling the respective second spring element 33′, 33″ or 33″′ to the base support 14 and/or to the support part 16. The coupling mechanism 34 is attached to the base support 14 and can (as will be specified in more detail below) be brought into different states, in which the coupling mechanism 34 interacts either with the respective second spring element 33′, 33″ or 33″′ such that the respective second spring element 33′, 33″ or 33″′ is in the coupled state and is capable in this state to generate a reset force, which acts on the support part 16 or interacts such that the respective spring element 33′, 33″ or 33″′ is in the uncoupled state and is not capable in this state to generate a reset force, which acts on the support part 16.

In the instant example, the coupling mechanism 34 comprises a total of three “coupling devices”, wherein one of these coupling devices is in each case assigned to one of the respective second spring elements 33′, 33″ or 33″′, respectively.

The “coupling device” assigned to the second spring element 33′ comprises:

-   -   a first holding means 36′ for holding a “first section” of the         spring element 33′, wherein the outer housing 44 of this spring         element is considered to be the “first section” of the spring         element 33′ and     -   a second holding means for holding a “second section” of the         spring element 33′, wherein the inner housing 43 of this spring         element is considered to be the “second section” of the spring         element 33′ and in this context the afore-mentioned second         holding means is understood to be the already mentioned positive         connection between the inner housing 43 of the spring element         33′ and the bearing shaft 18.

The first holding means 36′ for holding the outer housing 44 of the second spring element 36′ is embodied in the form of a movable part, which is attached to the base support 14 and which (as will be specified below in more detail) can be brought into a “first” position on the one hand, in which the first holding means 36′ is brought into contact with the outer housing 44 of the second spring element 33′ and holds the outer housing 44 in a predetermined position relative to the base support 14 and, on the other hand, can be brought into a “second” position, in which the first holding means 36′ is not in contact with the outer housing 44 of the second spring element 33′.

It follows from this that the first holding means 36′ is a means for holding the outer housing 44 of the second spring element 33′ so as to be capable of being detached, wherein the outer housing 44 is only held by the first holding means 36′ when the holding means 36′ is in the mentioned first position, and the outer housing 44 is separated (detached) from the first holding means 36′ in the event that the first holding means 36′ is in the second position.

The afore-mentioned “coupling device”, which is assigned to the second spring element 33′, has the characteristic that the outer housing 44 of the second spring element 33′ is connected to the base support 14 when the first holding means 36′ is brought into the mentioned first position and the inner housing 43 of the second spring element 33′ is rigidly connected to the bearing shaft 18 and is thus rigidly connected to the support part 16. In this case, the second spring element 33′ is in the already mentioned coupled state. However, if the first holding means 36′ is brought into the mentioned second position, the outer housing 44 of the second spring element 33′ is not connected to the base support 14. According to this assumption, the first spring element 33′ is in the uncoupled state. In this case, the second spring element 33′ is rotated together with the bearing shaft 18 as a whole in response to a rotation of the bearing shaft 18 about the longitudinal direction thereof. The inner housing 43 of the second spring element 33′ is not twisted relative to the outer housing 44 and the elastomer body 46 of the second spring element 33′ is not deformed. Accordingly, the second spring element 33′ cannot generate a reset force, which acts on the support part 16 and which counteracts this pivoting motion, in response to a pivoting motion of the support part 16, in the event that the first holding means 36′ is in the second position.

Those “coupling devices” of the coupling mechanism 34, which are assigned to the respective second spring elements 33″ and 33″′, are constructed analogous to those coupling devices, which were previously described in context with the second spring element 33′, with reference to their structure and function. Accordingly, the coupling mechanism 34 comprises (analogous to the first holding means 36′) a first holding means 36″ for detachably holding the outer housing 44 of the second spring element 33″ and a first holding means 36″′ for detachably holding the outer housing 44 of the second spring element 33″′. Accordingly, the coupling mechanism 34 furthermore comprises (analogous to the mentioned second holding means for the second spring element 33′) a second holding means for holding the inner housing 43 of the spring element 33′ (realized in the form of the already mentioned positive connection between the inner housing 43 of the second spring element 33″ and the bearing shaft 18) and a second holding means for holding the inner housing 43 of the second spring element 33″′ (realized in the form of the already mentioned positive connection between the inner housing 43 of the second spring element 33″′ and the bearing shaft 18).

As is suggested in FIGS. 4A and 4B, the first holding means 36′, 36″ and 36″″ are arranged next to one another in a row such that they can be pivoted about a pivot axis 37, which is oriented parallel to the bearing shaft 18 and which is arranged in a stationary manner relative to the base support 14. The first holding means 36′, 36″ and 36″′ can in each case be pivoted about the pivot axis 37 such that they can selectively be brought into contact with the outer housing 44 of the respective assigned second spring element 33′, 33″ or 33″′, respectively (in the first position of the respective holding means) or can be separated from the respective outer housing (in the second position of the respective holding means).

As is furthermore suggested in FIGS. 4A and 4B, the support structure 13 comprises an actuating means (control device) 38 for moving the respective first holding means 36′, 36″ and 36″′. In the instant example, the actuating means 38 comprises a rotatable cam shaft 39, on which cams 40′, 40″ and 40″′ are arranged, which in each case (in this order) are assigned to one of the first holding means 36′, 36″ and 36″′. The cams 40′, 40″ and 40″′ are formed such that they control the first holding means 36′, 36″ and 36″′ individually or in combination with one another in response to a rotation of the cam shaft 39 (about the longitudinal axis of the cam shaft 39), so as to pivot the first holding means 36′, 36″ and 36″′ in each case about the pivot axis 37 and, if necessary, to be able to bring them into contact with the outer housing 44 of the respective assigned second spring element 33′, 33″ or 33″′, respectively.

FIGS. 4A and 4B show the cam shaft 39 in a position, in which the respective cams 40′, 40″ and 40″′ are arranged such that all first holding means 36′, 36″ and 36″′ are arranged such that none of the first holding means 36′, 36″ and 36″′ is brought into contact with one of the second spring elements 33′, 33″ or 33″′, respectively. Accordingly, all second spring elements 33′, 33″ or 33″′, respectively, are in the uncoupled state. In this case, the first spring element 32 is accordingly coupled to the base support 14 as well as to the support part 16. In this case, only the first spring element 32 generates a reset torque acting on the bearing shaft 18 or on the support part 16, respectively, which counteracts the pivoting motion of the support part 16 or the rotation of the bearing shaft 18, respectively, in response to a pivoting motion of the support part 16 or in response to a corresponding rotation of the bearing shaft 18, respectively.

FIG. 4B shows the coupling mechanism 34 illustrated in FIG. 4A from a different perspective. Outer housing cams 42′-42″′, which are in each case attached or integrally molded to, respectively, to the outer housings 44 of the second spring elements 33′-33″′, can be identified hereby. These outer housing cams 42′-42″′ are arranged such that the first holding means 36′-36″′, which is brought into the first position by means of a corresponding actuation of the actuating means 38, is in each case brought into contact with the corresponding outer housing cams 42′-42″′ and forms a mechanical stop for this outer housing cam. The respective outer housing 44 of the respective second spring element 33′, 33″ or 33″′, respectively, is accordingly coupled to the base support 14 via the respective outer housing cam 42′-42″′ by means of the coupling mechanism 34.

FIGS. 5A-5C show a detailed view of the support structure 13, wherein the spring elements 32, 33′, 33″ or 33″′, respectively, and the coupling mechanism 34 of the power system are shown in different states. The support part 16 and the seat support 28 are not illustrated in FIGS. 5A-5C (for clarifying the illustrated facts).

The cams 40′-40″′ in FIG. 5A are oriented by means of a suitable rotation of the cam shaft 39 such that the first holding means 36′-36″′ is in the second position and are accordingly not brought into contact with the outer housing cams 42′-42″′ of the second spring elements 33′-33″′. All second spring elements 33′, 33″ or 33″′, respectively, are accordingly in the uncoupled state. The position of the bearing shaft 18 illustrated in FIG. 5A corresponds to the basic position of the support part 16. In this situation, none of the spring elements 32, 33′, 33″ or 33″′, respectively, generates a reset torque, which acts on the bearing shaft 18. Based on the position of the bearing shaft 18 illustrated in FIG. 5A, the bearing shaft 18 can be rotated in the direction of the arrow 18′, so as to provide for a pivoting motion of the support part 16. Such a rotation can be caused, for example, by a person sitting on the seat assembly 10 according to FIG. 1 when leaning back against the backrest 22. In response to a rotation of the bearing shaft in the direction of the arrow 18′, only the first spring element 32 would generate a reset torque acting on the bearing shaft 18 (according to the situation illustrated in FIGS. 4A and 4B).

FIG. 5B illustrates a state of the power system 30, which differs from the state illustrated in FIG. 5A in that the first holding means 36″′ is now in the first position (and is accordingly brought into contact with the outer housing cam 42″′ of the second spring element 33″′, which is not visible in FIG. 5B). The state of the power system 30 in FIG. 5B also differs from the state illustrated in FIG. 5A in that the bearing shaft 18 is rotated counter clockwise about a certain angle of rotation (that is, in the direction of the arrow 18′). Accordingly, the coupling mechanism 34 is in a state, in which the second spring element 33″′ is in the coupled state and the second spring elements 33′ and 33″ are in the uncoupled state. As becomes clear from a comparison with FIG. 5A, the spatial position of the outer housing 44 of the first spring element 32 and the spatial position of the outer housing of the second spring element 33″′ is unchanged in the state according to FIG. 5B (as compared to the situation according to FIG. 5A), while the respective inner housings 43 of the spring elements 32 and 33″′ are rotated about the axis of rotation of the bearing shaft 18 in the direction of the arrow 18′ together with the bearing shaft 18 (due to the rigid coupling of the inner housings of the spring elements 32 and 33″′ to the bearing shaft 18). The spring elements 32 and 33″′ accordingly generate a reset torque in each case, which acts on the bearing shaft 18 (contrary to the rotation of the bearing shaft 18 in the direction of the arrow 18′).

As becomes clear from a comparison with FIG. 5A, the second spring elements 33′ and 33″ are rotated as a whole in the direction of the arrow 18′ about the axis of rotation of the bearing shaft 18 in the state according to FIG. 5B, in particular because the outer housing 44 of the second spring elements 33′ and 33″ are not coupled to the base support 14 by means of the first holding means 36′ or 36″, respectively. According to this, the second spring elements 33′ and 33″ do not generate a reset torque acting on the bearing shaft 18 in the situation according to FIG. 5B.

FIG. 5C shows a state of the power system 30 or of the coupling mechanism 34, respectively, in which all second spring elements 33′-33″′ are in the coupled state: by means of a suitable rotation of the cam shaft 39, the cams 40′-40″′ are oriented such that the first holding means 36′-36″′ are in the first position and are accordingly brought into contact with the outer housing cams 42′-42″′ of the second spring elements 33′-33″′. In this situation, the outer housings 44 of all of the spring elements 32, 33′-33″′ are locked in a stationary position relative to the base support 14. In response to a rotation of the bearing shaft 18 in the direction of the arrow 18′, the inner housing of the respective spring element 32, 33′-33″′ would accordingly be twisted in each case relative to the outer housing 44 of the respective spring element 32, 33′-33″′, so that all of the spring elements 32, 33′-33″′ in each case generate a reset torque, which acts on the bearing shaft 18.

As specified above, a (total) reset torque acts on the bearing shaft 18 in each case, with said reset torque corresponding to the sum of all of the reset torques generated by those spring elements 32, 33′-33″′, which are in each case in the coupled state and are accordingly coupled to the base support 14 as well as to the support part 16. Due to the fact that only the first spring element 32 is in the coupled state in the state of the power system 30 illustrated in FIG. 5A, the power system 30 in the state according to FIG. 5A generates a reset torque with the smallest possible value, in response to a rotation of the bearing shaft 18 by a predetermined angle of rotation φ and is thus adjusted in this state to persons having a relatively low weight. Due to the fact that, in the state of the power system 30 illustrated in FIG. 5C, all second spring elements 33′-33″′ are in the coupled state in addition to the first spring element 32, the power system 30 generates a reset torque with the largest possible value in response to a rotation of the bearing shaft 18 about the same (above-mentioned) angle of rotation φ and is thus adjusted in this state to persons having a relatively large weight.

In the state according to FIG. 5B, the power system 30 accordingly generates a reset torque in response to a rotation of the bearing shaft 18 about the same (above-mentioned) angle of rotation φ, the value of which lies between the corresponding values of the reset torque generated by the power system 30 in the states according to FIGS. 5A and 5C and is thus adjusted to persons having an average weight.

FIGS. 6A and 6B show a schematic view of the power system 30 together with the coupling mechanism 34 and actuating means 38, wherein the base support 14 is not illustrated, so as to more clearly show details of the individual spring elements 32, 33′-33″′ (in particular the outer contours thereof and the arrangement thereof on the bearing shaft 18). In the example according to FIG. 6A, the cam shaft 39 is rotated such that the cams 40′-40″′ are positioned such that only the first holding means 36′ is brought into the first position and only the second spring element 33′ (except for the first spring element 32) is thus in the coupled state. FIG. 6B shows the coupling mechanism 34 in a state, in which none of the second spring elements 33′-33″′ is transferred into the coupled state. Accordingly, the situation illustrated in FIG. 6B is identical to the situation illustrated in FIG. 5A.

FIG. 7A shows a schematic side view of the second spring element 33′ in a sectional plane, which is perpendicular to an axis of rotation 47. The spring elements 32, 33″ and 33″′ are identical to the spring element 33′ with reference to their structural design, so that the characteristics of the spring elements 32 and 33′-33″ are to be specified below by means of the spring element 33′ according to FIG. 7A. As already mentioned, the second spring element 33′ (as are the spring elements 32, 33″ and 33″′) is embodied as an elastomer torsion spring element and comprises an inner housing 43 and an outer housing 44. An elastomer body 46 is arranged in a space between the inner housing 43 and the outer housing 44.

On its outer side, the inner housing 43 encompasses a contact surface 43 a, on which the elastomer body 46 is in contact with the inner housing 43. On its inner side, the outer housing 44 furthermore encompasses a contact surface 44 a, on which the elastomer body 46 is in contact with the outer housing 44. The contact surface 43 a of the inner housing 43 and the contact surface 44 a of the outer housing 44 enclose the axis of rotation 47 in a ring-shaped manner in each case. Accordingly, the elastomer body 46 in the instant example forms a closed ring, which surrounds the axis of rotation 47.

The elastomer body 46 consists of an elastomer, that is, a fixed and elastically deformable material. The elastomer body 46 is embodied such that it is fixedly connected to the contact surface 43 a of the inner housing 43 and to the contact surface 44 a of the outer housing 44. That is, a displacement of the surfaces of the elastomer body 46 abutting on the contact surfaces 43 a and 44 a relative to the contact surfaces 43 a and 44 a does not take place in response to a movement of the inner housing 43 relative to the outer housing (e.g. in response to a rotation of the inner housing 43 or of the outer housing 44 about the axis of rotation 47). The elastomer body 46 can be connected to the inner housing 43 and to the outer housing 44 by means of material engagement or in a form-fit manner on the contact surfaces 43 a or 44 a, respectively.

An elastomer, which is particularly well-suited for the production of the elastomer body 46, is a rubber, for example, which is not only an elastically deformable and high-tensile material, but which can also be fixedly connected to the contact surfaces 43 a and 44 a in a simple manner such as, for example, by means of vulcanizing.

The inner housing 43 and the outer housing 44 are made from a solid material such as, for example, steel. The respective contact surfaces 43 a and 44 a of the inner housing 43 or of the outer housing 44, respectively, which in each case adjoin the elastomer body 46—in a sectional plane, which is perpendicular to the axis of rotation 47—differ from a circular design, at least in sections. Due to this special form, pressure loads, which compensate tensile forces therein, appear in several areas of the elastomer body 46, in response to the rotation of the inner housing 43 about the axis of rotation 47 in relation to the outer housing 44. The elastomer body 46 is thus not loaded in a homogenous manner.

In FIG. 7A, the inner housing 43 is shown in an “untwisted” state (solid line) and in a “twisted state” (dotted line). In the twisted state, as compared to the untwisted state, the inner housing 43 is twisted clockwise about an angle of rotation φ about the axis of rotation 47, while the position of the outer housing 44 remains unchanged thereby. It is assumed that the elastomer body 46 is not prestressed in the case of the untwisted state, that is, that is does not encompass any mechanical stresses. In the untwisted state, the distances from the upper right-hand corner or the lower left-hand corner, respectively, of the inner housing 43 to respective defined points on the inner side of the outer housing 44 are in each case shown by means of arrows x1 or y1, respectively. In the twisted state, the distances from the upper right-hand corner or the lower left-hand corner, respectively, of the inner housing 43 to respective defined points on the inner side of the outer housing 44 are in each case identified by means of arrows x2 or y2, respectively. As can be seen in FIG. 7A, the distance x2 is smaller than x1 and the distance y2 is smaller than y1. The elastomer body 46 is thus compressed in this area when the inner housing 43 is rotated about the axis of rotation 47 and is thereby rotated relative to the outer housing 44. The above-mentioned pressure loads result from these respective compressions.

After a rotation of the inner housing 43 about the angle of rotation φ about the axis of rotation 47, the elastomer body 46 is deformed and generates a reset torque D between the outer housing 44 and the inner housing 43, which is directed opposite to the rotation and which increases with the angle of rotation φ.

The fact that the distances x2-xl and y2-y2 are reduced in response to a rotation of the inner housing 43 about the angle of rotation φ, is a result of the fact that the cross section of the contact surface 43 a or of the contact surface 44 a, respectively is not circular (in a cutting surface vertical to the axis of rotation 47). The result of the geometric deviation of the mentioned cross sections of the contact surfaces 43 a or 44 a, respectively, from a circularity is that, in response to a rotation of the inner housing 43 about the angle of rotation φ, a spatial distribution of the mechanical stress results in the elastomer body 46, which is not rotationally symmetrical to the axis of rotation 47. This is contrary to the spatial distribution of the mechanical stresses in an elastomer torsion spring element according to EP 1486142 A1, which is rotationally symmetrical to the axis of rotation 47 in each case. These differences with reference to the stress distribution lead to considerable differences with reference to the dependencies of the reset torque D as a function of the angle of rotation φ. In particular, these differences cause an elastomer torsion spring element comprising the form illustrated in FIG. 7A to show a considerably greater increase of the reset torque D as function of the angle of rotation φ than the elastomer torsion spring element according to EP 1486142 A1.

In the embodiment illustrated in FIG. 7A, the contact surface 43 a of the inner housing 43, which adjoins the elastomer body 46, is formed so as to be square. The inner housing 43 is hereby embodied as a square sleeve (square), which encompasses a channel 43.1 comprising a square cross section and extending parallel to the axis of rotation 47. The shape of the cross section of the channel 43.1 is adapted to the cross sectional shape of the bearing shaft 18, so that the bearing shaft 18 can be inserted through the channel 43.1 and the inner housing 43 can sit on the bearing shaft 18—being connected to the bearing shaft 18 in a positive fit (as already mentioned in context with FIGS. 4A and 4B).

The contact surface 44 a of the outer housing 44 adjoining the elastomer body 46 has a contour, which is to be considered to be a combination of a rectangle and a circle. More specifically, the contour of the outer housing 44 is comprised of two equal-legged angular segments, which are located opposite one another in pairs and which draw an angle of 90° in the instant example, and of two semi circle segments, which are located opposite to one another in pairs and the ends of which are in each connected to the ends of the mentioned angular segments. By means of a plurality of test series, which were carried out, it was determined that this seemingly “lemon-shaped” contour of the outer housing 44, in combination with the square contour of the inner housing 43, is particularly advantageous for creating an elastomer torsion spring element, the characteristic curve of the reset torque D of which runs linear in virtually all areas of the angle of rotation φ in relation to the angle of rotation φ.

FIG. 7A further shows the outer housing cam 42′, which is embodied on the outer housing 44 and which was already mentioned in context with FIGS. 4B and 5A-5C.

FIG. 7B shows the second spring element 33′ illustrated in FIG. 7A with a holding element 48 in a perspective illustration. The holding element 48 serves the purpose of holding the inner housing 43 and the outer housing 44 in a “basic position” relative to one another, in which the elastomer body 46 encompasses a mechanical stress (prestress) and thus generates a reset torque D between the inner housing 43 and the outer housing 44, which is different from zero. In this “basic position”, the inner housing 43 is twisted about an angle of rotation Δφ (hereinbelow referred to as “prestress angle”) as compared to the “untwisted” position (without prestress) according to FIG. 7A, namely clockwise with reference to FIG. 7A and counter clockwise with reference to FIG. 7B. In this example, the holding element 48 includes two clamping elements 49, which are in each case attached to one of the front sides of the second spring element 33′.

The clamping element 49 is a substantially flat plate, the center area of which is punched such that two flanges 50′, 50″, which are located opposite one another, remain. These flanges are in each case curved inward by 90° (into the figure plane). Straps 52′, 52″, which are also curved inward by 90°, are embodied on an outer area of the clamping element 49.

For assembling the respective clamping element 49 to the second spring element 33′, the flanges 50′, 50″, which are embodied such that the outer areas thereof can be connected to the inner surface of the inner housing 43 in a positive fit, are inserted into the inner housing 43 about a first distance. Then, the clamping element 49 and the inner housing 43, which is connected thereto in a positive fit in radial direction, are twisted counter clockwise about a certain angle (for example) 20° in relation to the outer housing 44.

Subsequently, the clamping element 49 is pushed completely into the channel 43.1 of the inner housing 43 with its flanges 50′, 50″, wherein the straps 52′, 52″ assume a positive connection with the outer surface of the outer housing at the same time. Assembled in this manner, the clamping element 49 maintains the prestress. More specifically, the prestress angle Δ® can no longer be fallen below, because the straps 52′, 52″ strike against the outer surface of the outer housing 44. However, an increase of the rotational displacement (also counter clockwise) between the inner housing 43 and the outer housing 44 is possible. In response to an increase of this rotational displacement, the inner areas of the straps 52′, 52″ slide along the outer surface of the outer housing 44 or are removed therefrom. To prevent a destruction of the second spring element 33′, a maximum angle of rotation (for example 70°) is not to be exceeded between the inner housing 43 and the outer housing 44 in this example. This is so, because the strap 52′ strikes against the outer housing cam 42′ in the case of the maximum angle of rotation φ, thus advantageously preventing a further rotation.

The clamping element 49 can also be used in combination with the spring elements 32, 33″ and 33″′ analogous to the example illustrated in FIG. 7B. It is pointed out that in the case of the power system 30, the respective second spring elements 33′, 33″ and 33′″ are in each case illustrated in combination with two clamping elements 49 in the illustrations according to FIGS. 4A, 4B, 5A-5C, 6A and 6B, which corresponds to the clamping elements 49 according to FIG. 7B (as is suggested in particular in FIGS. 6A and 6B).

Accordingly, each of the second spring elements 33′, 33″ and 33″′ of the power system 30 generates a reset torque, which acts on the bearing shaft 18 in each case, in response to a rotation of the bearing shaft 18, with said reset torque being greater or equal to a predetermined minimum value (different from zero), provided that the respective second spring element 33′, 33″ or 33″′, respectively, is in the coupled state.

FIGS. 8A-8C show (in different views) an alternative of the power system 30 according to FIGS. 3A-6B. The power system 30 according to FIGS. 8A-8C differs from the power system 30 according to FIGS. 3A-6B substantially in that it comprises clamping elements 54′, 54″, 54″′ and 54″″ (as replacement for the type of clamping elements 49 shown in FIG. 7B). Clamping elements 54′, 54″, 54″′ and 54″′ differ from the clamping elements 49 according to FIG. 7B with reference to their construction. The alternative of the power system 30 according to FIGS. 8A-8C accordingly also comprises (as does the power system 30 according to FIG. 3A-6B) the bearing shaft 18, the first spring element 32 and the second spring elements 33′, 33″ and 33″′. The coupling mechanism 34 and the actuating means 38 are not illustrated in FIGS. 8A-8C.

The clamping elements 54′-54″″ are plate-like elements, the inner areas of which are punched in a rectangular manner. The contour of the punch is hereby adapted in a positive fit to the outer contour of the (square) bearing shaft 18. Curvatures 55′-55″″, which in each case include a through hole, are integrally molded on the outer areas of the clamping elements 54′-54″″.

In response to the assembly of the power system 30, the bearing shaft 18 and the inner housing 32 of the first spring element 32 are connected to one another in a positive fit in radial direction. A first clamping element 54′ is subsequently attached onto the bearing shaft 18 across its punch, so that a positive connection in radial direction is also established between the bearing shaft 18 and the clamping element 54′. The second spring element 33′ is subsequently attached to the bearing shaft 18. Following this step, a further clamping element 54″ is attached, etc. After all three second spring elements 33′-33″′ have been attached onto the bearing shaft 18 with clamping elements 54′-54″′, which have been placed therebetween in each case, the last clamping element 54″″ is finally attached on the front side.

Subsequently, the second spring elements 33′-33″′ are prestressed either individually or at the same time, in that their outer housings, for example, are rotated clockwise about the longitudinal direction of the bearing shaft 18 in response to a radially fixed bearing shaft 18. This rotation takes place up to an angle or rotation, at which pins 56′, 56″ can be inserted through the respective holes of the curvatures 55′-55″″. After the pins 56′, 56″ have been inserted through these holes, the introduction of force for turning the outer housings is ended. In this state, the outer housings 44 of the individual second spring elements 33′-33″′ remain in this position, because the respective outer surfaces of the outer housings 44 now strike against a peripheral section of the pins 56′, 56″. It is thus now no longer possible for the respective outer housings 44 to be turned back into the initial state.

An advantage of the arrangement and of the embodiment of the clamping elements 54′-54″″ is that, contrary to the examples shown in FIGS. 6A, 6B and 7B, a flange is now no longer inserted into the respective inner housings 43 of the second spring elements 33′-33″′. The bearing shaft 18 is thus in a positive engagement in radial direction with the entire inner surface of the respective inner housings 43. A play between the bearing shaft 18 and the inner housing 43 of the respective second spring element 33′-33″′ is thus avoided. A bearing clearance, however, appears in the case of the example illustrated in FIGS. 6A and 6B, which is based on the fact that introduction of the reset torques of the respective second spring elements 33′-33″′ into the bearing shaft 18 takes place section by section via the flanges 50′, 50″ of the respective clamping element 49 and that the inner housings 43 of the respective second spring elements 33′-33″′ can accordingly not be in mechanical contact with the bearing shaft 18 (see FIGS. 6A, 6B and 7B).

A further advantage of the example shown in FIGS. 8A-8C lies in that the assembly is much simpler as compared to the example illustrated in FIGS. 6A and 6B, in the case of which each elastomer torsion spring element was first equipped with its clamping elements 49.

In addition, the assembly time is markedly shortened. A further advantage lies in the much simpler and less time-intensive production of the individual clamping element 54′-54″″. They can only be produced in a cost-efficient manner by means of punches.

FIGS. 9A-9E show different views of a clamping device 58 for prestressing the spring elements 33′-33″′ shown in FIGS. 8A-8C comprising the clamping elements 54′-54″″ attached therebetween and on the front side. In FIGS. 9A and 9C, the clamping device 58 is in each case illustrated in full view, viewed from different directions. In FIGS. 9B and 9D, the clamping device 58 is in each case illustrated in a detailed view, viewed from different directions. The clamping device 58 serves to easily and quickly prestress the individual spring elements 33′-33″′ with only a few steps. The clamping device 58 includes fixing devices 60, which fix the bearing shaft 18 (not shown) so as to be fixed on its axial ends. As is specified for describing FIGS. 8A-8C, the individual spring elements 33′-33″′ are first attached to the bearing shaft 18, wherein the clamping elements 54′-54″″ are in each case attached therebetween and on the front side. These clamping elements 54′-54″″ are in each case connected to the bearing shaft 18 in a positive fit in radial direction.

The clamping device 58 further includes a rod 62, which is connected vertically between two lever arms of a lever 64. The lever arms are pivotably articulated via clamping device bearings 66′, 66″. The lever 64 can be deflected back and forth at its lower end via a drive 68. In response to a deflection of the lower section of the lever 64 in a direction out of the figure plane of FIG. 9A, the rod 62 is deflected towards the spring elements 33′-33″′, as is suggested by an arrow A.

As can be seen particularly well in FIGS. 9C-9E, a surface area of the rod 62 initially engages with an area of the outer surface of the outer housing of a first spring element, in this example with the outer housing 44 of the second spring element 33″′ (for example via the outer housing cam 42″′) in a first stage of the deflection of the rod 62 in the direction of the arrow A.

Starting at a second stage of the deflection of the rod 62 in the direction of the arrow A, a further surface area of the rod 62 engages with the outer surface of the outer housing of a further spring element, in this example with the outer housing 44 of the second spring element 33″. During the deflection of the rod 62 between the first stage and the second stage, the outer surface of the outer housing 44 of the second spring element 33″′, which was previously brought into engagement, is also rotated or twisted, respectively. In a third stage of the deflection of the rod 62 in the direction of the arrow A, an area of the outer surface of the outer housing of a further spring element, in this example the outer housing 44 of the second spring element 33′, is engaged. During the deflection of the rod 62 between the second stage and the third stage, the second spring elements 33″′ and 33″ are deflected or twisted, respectively. In a fourth stage of the deflection of the rod 62, all spring elements 33′-33″′ are now deflected or twisted, respectively, parallel to one another such that the pins 56′, 56″, which are also illustrated in FIGS. 8A-8C, can be inserted through the holes of the respective curvatures 55′-55″″ of the individual clamping elements 54′-54″″. As soon as the pins 56′, 56″ have been inserted through the mentioned holes, the mentioned deflection of the rod 62 is reversed, that is, the rod is moved opposite to the arrow direction A. The used pins 56′, 56″ abut on the individual outer surfaces of the outer housings of the second spring elements 33′-33″′ and are clamped due to the effect of the reset torques of the second spring elements 33′-33″′. The pins 56′, 56″ are furthermore in each case held by means of the clamping elements 54′-54″″, which are coupled in a torsionally rigid manner in radial direction. The individual second spring elements 33′-33″′ can thus no longer return into the respective non-deflected initial state (FIGS. 9A-9E).

FIG. 9E shows the clamping device 58 in a view in axial direction to the clamping device bearings 66′, 66″. It can be seen particularly clearly in this figure that the individual second spring elements 33′-33″′ are deflected differently in each case in their initial state. This is due to the fact that the respective inner housings of the second spring elements 33′-33″′ are arranged in relation to the contour of their respective outer housings in each case comprising a rotational displacement, which has a different size for the second spring elements 33′-33″′ in each case. The rotational displacements for the second spring elements 33′-33″′ can be 20°, 25° and 40° for example. Due to the respective different rotational displacement between the inner housing 43 and the outer housing 44, the individual second spring elements 33′-33″′ are thus also prestressed to varying degrees. In this example, the second spring element 33″′ is thus prestressed more than the second spring element 33″, which in turn is prestressed less than the second spring element 33′. As is suggested in FIGS. 9A and 9C-9E, the pins 56′, 56″ can be inserted through the holes of the curvatures 55′-55″″ of the respective clamping elements 54′-54″″ after the prestressing. The respective prestressing of the individual second spring elements 33′-33″′ is thus maintained by means of the pins 56′, 56″.

This prestress cannot be fallen below, but the outer housings 44 of the individual second spring elements 33′-33″′ can be further rotated relative to the corresponding inner housings 43 in a direction of rotation such that the reset torque generated by the respective second spring element 33′-33″′ is increased as the angle of rotation increases, until the outer housing cams 42′-42″′, which are integrally molded on the respective outer housing 44, strike against the pin 56′. In this state, the second spring elements 33′-33″′ have reached their maximally permissible angle of rotation and in each case provide for the largest possible reset torque.

The clamping device 58 illustrated in FIGS. 9A-9E and the methods described with reference thereto in an exemplary manner show that the afore-described power system 30 can be produced very quickly and with only a few movements even in the case of differently prestressed second spring elements 33′-33″′.

FIG. 10A shows a support structure 13 a according to another embodiment of the invention, which represents an alternative of the support structure 13 according to FIG. 2. Those components, which together encompass the support structures 13 and 13 a will be identified hereinbelow with the same reference numerals.

The support structure 13 a according to FIG. 10A comprises—as does the support structure 13 according to FIG. 2—a base support 14 and a support part 16 (for supporting and/or holding the back part 20 and/or the respective seat 24 according to FIG. 1). The support part 16 is connected to the ends of a rotatable bearing shaft 18 via a connecting piece 26 in a torsionally rigid manner, so that the support part 16 can be pivoted in the direction of the arrow 18′ about the longitudinal axis of the bearing shaft 18.

FIG. 10B also shows the support structure 13 a according to FIG. 10A the only difference being that the support part 16 is not illustrated in FIG. 10B.

The support structure 13 a comprises a power system 30 a, which comprises two first spring elements 32 a and second spring elements 33′, 33″ and 33″′. The spring elements 32 a, 33′, 33″ and 33″′ are in each case designed as elastomer torsion spring element and are identical with the spring element 33′ according to FIG. 7A with reference to their structure. That is, the spring elements 32 a, 33′, 33″ and 33″′encompass in each case an inner housing 43, an outer housing 44 surrounding the inner housing 43, and an elastomer body 46, which is arranged in the space between the inner housing 43 and the outer housing 44, and which is fixedly connected to the inner housing 43 and the outer housing 44. The second spring elements 33′, 33″ and 33″′ of the power system 30 a are identical with the spring elements 33′, 33″ and 33″′ of the power system 30. With reference to its construction, the first spring element 32 a of the power system 30 a differs from the first spring element 32 of the power system 30 substantially in the shape of the cross section of the outer housing 44, as is suggested in FIG. 10B. The latter, however, is not important with reference to the function of the first spring element 32 a in this context.

As is suggested in FIG. 10B, the spring elements 32 a, 33′, 33″ and 33″′ of the power system 30 a are located on the bearing shaft 18 such that the inner housing 43 of the spring elements are in each case connected to the bearing shaft in a torsionally rigid manner. As is further suggested in FIG. 10B, the outer housing 44 of the respective first spring element 32 a is connected to the base support 14 in a torsionally rigid manner, while the inner housing 43 together with the bearing shaft 18 can be rotated in the direction of the arrow 18′. The two first spring elements 32 a are accordingly coupled to the base support 14 as well as to the support part 16, so that the first spring elements 32 a generate a reset torque in each case in response to a pivoting motion of the support part in the direction of the arrow 18′, with said torque being oriented opposite to the pivoting motion of the support part 16.

The second spring elements 33′, 33″ and 33″′ of the power system 33 a correspond to the second spring elements 33′, 33″ and 33″′ of the power system 30 from a functional point of view. The support structure 13 a also comprises the same coupling mechanism 34 and the actuating means 38 for controlling the coupling mechanism such that the respective second sprig elements 33′, 33″ and 3″′ can be brought either into the coupled state (in which the respective second spring element 33′, 33″ and 33″′ is coupled to the base support 14 as well as to the support part 16 via the coupling mechanism 34) or into the uncoupled state (in which the respective spring element 33′, 33″ and 33″′ is not coupled to the base support 14 and/or to the support part 16).

An important feature of the support structure 13 a is to be seen in that the support part 16 and the two ends of the bearing shaft 18 are always coupled to the base support 14 via the elastomer bodies 46 of the two first spring elements 32 a, wherein the elastomer bodies 46 can accommodate a load, which acts radially on the bearing shaft 18. In the case of the support structure 13 a, the bearing shaft 18 accordingly does not require a separate swivel, which supports the bearing shaft 18 rotatably on the base support 14. In the instant case, the first spring elements 32 a serve as bearing for the bearing shaft 18, in particular when none of the second spring elements 33′-33″′ is switched into the coupled state. In the event that one of the second spring elements 33′-33″′ is in the coupled state, this spring element also serves as support for the bearing shaft 18 with reference to the base support 14.

The spring elements 32 a thus carry out a double function: as means for generating a reset force/torque acting on the support part 16 and as bearing for the support of the bearing shaft 18. An advantage of this arrangement lies in that separate swivels are not necessary through this. Costs are thus reduced. In addition, this arrangement saves space. A further advantage lies in that forces appearing radially to the bearing shaft 18 can be accommodated by means of the elastomer body 46 between the inner housing 43 and the outer housing 44 of the first spring element 32 a. This arrangement thus achieves an advantageous elastic coupling between the base support 14 and the support part 16, which increases the seating comfort.

While the invention has been described and illustrated with reference to certain particular embodiments thereof, those skilled in the art will appreciate that various adaptations, changes, modifications, substitutions, deletions, or additions of procedures and protocols may be made without departing from the spirit and scope of the invention. It is intended, therefore, that the invention be defined by the scope of the claims that follow and that such claims be interpreted as broadly as is reasonable. 

1. A support structure for a back part and/or a seat of a seat assembly, comprising: a base support; a support part arranged on the base support and configured to support and/or hold the respective back part and/or the respective seat, said support part being attached to the base support to allow relative movement of the support part relative to the base support; a power system configured to generate a reset force in response to the respective movement of the support part, wherein the reset force is directed opposite to the movement, wherein the power system comprises a first spring element coupled to the base support and to the support part, wherein, in response to the respective movement of the support part, the first spring element is configured to generate a first reset force directed opposite to the respective movement of the support part; a second spring element; and a coupling device configured to couple the respective second spring element to the base support and/or to the support part, wherein the coupling device is configured to be brought either into the first or into a second state, wherein, in the event that the coupling device is in the first state, the respective second spring element is coupled to the base support and to the support part, whereby, in response to the respective movement of the support part, the respective second spring element generates a second reset force directed opposite to the respective movement of the support part, and wherein, in the event that the coupling device is in the second state, the respective second spring element is not coupled to the base support and/or to the support part, whereby the respective second spring element does not generate a second reset force directed opposite to the respective movement of the support part.
 2. The support structure according to claim 1, further comprising a control device configured to adjust the respective state of the respective coupling device, whereby the respective coupling device is brought either into the first or into the second state.
 3. The support structure according to claim 1, further comprising a plurality of the second spring elements and a plurality of the coupling devices, wherein the plurality of coupling devices are configured to be brought into the first or into the second state independent from one another.
 4. The support structure according to claim 3, wherein all of the plurality of coupling devices are in the second state so that none of the second spring elements are coupled to the base support and to the support part.
 5. The support structure according to claim 3, wherein one of the plurality of coupling devices is in the second state so that a corresponding one of the second spring elements is coupled to the base support and to the support part.
 6. The support structure according to claim 3, wherein at least two of the plurality of coupling devices are in the second state so that at least two of the second spring elements are coupled to the base support and to the support part.
 7. The support structure according to claim 1, wherein the second spring element comprises a first section and a second section configured to be moved relative to one another to generate the respective reset force, and wherein the coupling device comprises: first holding means for holding the first section of the respective second spring element, said first holding means connected to the base support and configured to interact with the first section of the respective second spring element, whereby, when the coupling device is brought into the first state, the first section of the respective second spring element is held in a predetermined position relative to the base support; and second holding means for holding the second section of the respective second spring element, said second holding means connected to the support part and configured to interact with the second section of the respective second spring element, whereby, when the coupling device is brought into the first state, the second section of the respective second spring element is held in a predetermined position relative to the support part.
 8. The support structure according to claim 7, wherein, when the coupling device is brought into the second state, the first holding means is detached from the first section of the respective second spring element in response to the respective movement of the support part.
 9. The support structure according to claim 8, wherein the first holding means is moveable between at least two different positions, wherein, in one of the positions, the first holding means is in contact with the first section of the respective second spring element such that the first section is held in the predetermined position relative to the base support, and, in the other one of the positions, the first holding means is separated from the first section of the respective second spring element.
 10. The support structure according to claim 9, further comprising actuating means for moving the respective first holding means from one of the positions into the other one of the positions.
 11. The support structure according to claim 10, wherein the actuating means comprises a rotatable cam shaft including at least one cam assigned to the respective first holding means, wherein the respective first holding means are moveable by the respective assigned cam in response to a rotation of the cam shaft.
 12. The support structure according to claim 7, wherein, when the coupling device is brought into the second state, the second holding means is detached from the second section of the respective second spring element in response to the respective movement of the support part.
 13. The support structure according to claim 12, wherein the second holding means is movable between at least two different positions, wherein, in one of the positions, the second holding means is in contact with the second section of the respective second spring element such that the second section is held in the predetermined position relative to the support part, and, in the other one of the positions, the second holding means is separated from the second section of the respective second spring element.
 14. The support structure according to claim 1, wherein the respective first spring element comprises an elastomer torsion spring element including an inner housing, an outer housing surrounding the inner housing, and an elastomer body arranged in a space between the inner housing and the outer housing, wherein said inner housing comprises at least one contact surface in contact with, and fixedly connected to, the elastomer body, wherein said outer housing comprises at least one contact surface in contact with, and fixedly connected to, the elastomer body, wherein at least one of the inner housing and the outer housing is arranged so as to be rotatable relative to the other about an axis of rotation, wherein the elastomer torsion spring element is coupled to the base support and to the support part such that respective movement of the support part causes a rotation of the inner housing and/or of the outer housing about the axis of rotation, whereby relative rotation between the inner housing and the outer housing generates a deformation of the elastomer body, which deformation generates a reset torque between the inner and outer housings, said reset torque being directed opposite to the rotation.
 15. The support structure according to claim 14, wherein the support part is attached to a bearing shaft supported on the base support, whereby the support part is pivotable about a pivot axis, wherein one of the inner and outer housings is rigidly connected to the base support, and wherein the other of the inner and outer housings is rigidly connected to the support part or to the bearing shaft.
 16. The support structure according to claim 14, wherein the contact surface of at least one of the inner and outer housings comprises a non-circular cross section in a sectional plane perpendicular to the axis of rotation.
 17. The support structure according to claim 14, further comprising a holding element arranged on the respective elastomer torsion spring element, wherein the holding element is configured to hold the inner housing of the elastomer torsion spring element in a predetermined basic position relative to the outer housing of the elastomer torsion spring element, wherein the elastomer body comprises a predetermined elastic deformation in said basic position and generates a reset torque between the outer housing and the inner housing having a predetermined minimum value, and wherein the holding element is configured to release a rotation of the inner housing relative to the outer housing about an angle of rotation about the axis of rotation in a direction of rotation, the reset torque increasing as the angle of rotation increases.
 18. The support structure according to claim 17, wherein the holding element includes at least one clamping element comprising a first section fixedly engaged with one of the inner and outer housings; and a second section striking against a section of the other of the inner and outer housings when the inner housing is in the predetermined basic position relative to the outer housing, wherein the clamping element allows relative rotation between the inner and outer housings about the axis of rotation in the direction of rotation, whereby the reset torque increases.
 19. The support structure according to claim 18, wherein the inner housing comprises a recess and the first section of the clamping element is inserted into the recess in the inner housing in a torsionally rigid manner, and wherein, when the inner housing is in the predetermined basic position relative to the outer housing, the second section of the clamping element strikes against a section of the outer housing.
 20. The support structure according to claim 1, wherein the respective second spring element is an elastomer torsion spring element including an inner housing, an outer housing surrounding the inner housing, and an elastomer body arranged in a space between the inner housing and the outer housing, wherein said inner housing comprises at least one contact surface in contact with, and fixedly connected to, the elastomer body, wherein said outer housing comprises at least one contact surface in contact with, and fixedly connected to, the elastomer body, wherein at least one of the inner housing and the outer housing is arranged so as to be rotatable relative to the other about an axis of rotation, wherein, when the coupling device is brought into the first state, the elastomer torsion spring element is coupled to the base support and to the support part such that respective movement of the support part causes a rotation of the inner housing and/or of the outer housing about the axis of rotation, whereby relative rotation between the inner housing and the outer housing generates a deformation of the elastomer body, which deformation generates a reset torque between the inner and outer housings, said reset torque being directed opposite to the rotation.
 21. The support structure according to claim 20, wherein the support part is attached to a bearing shaft supported on the base support, whereby the support part is pivotable about a pivot axis, and wherein, when the coupling device is brought into the first state, one of the inner and outer housings is rigidly connected to the base support, and the other of the inner and outer housings is rigidly connected to the support part or to the bearing shaft.
 22. The support structure according to claim 20, wherein the contact surface of at least one of the inner and outer housings comprises a non-circular cross section in a sectional plane perpendicular to the axis of rotation.
 23. The support structure according to claim 20, further comprising a holding element arranged on the respective elastomer torsion spring element, wherein the holding element is configured to hold the inner housing of the elastomer torsion spring element in a predetermined basic position relative to the outer housing of the elastomer torsion spring element, wherein the elastomer body comprises a predetermined elastic deformation in said basic position and generates a reset torque between the outer housing and the inner housing having a predetermined minimum value, and wherein the holding element is configured to release a rotation of the inner housing relative to the outer housing about an angle of rotation about the axis of rotation in a direction of rotation, the reset torque increasing as the angle of rotation increases.
 24. The support structure according to claim 23, wherein the holding element includes at least one clamping element comprising a first section fixedly engaged with one of the inner and outer housings; and a second section striking against a section of the other of the inner and outer housings when the inner housing is in the predetermined basic position relative to the outer housing, wherein the clamping element allows relative rotation between the inner and outer housings about the axis of rotation in the direction of rotation, whereby the reset torque increases.
 25. The support structure according to claim 24, wherein the inner housing comprises a recess and the first section of the clamping element is inserted into the recess in the inner housing in a torsionally rigid manner, and wherein, when the inner housing is in the predetermined basic position relative to the outer housing, the second section of the clamping element strikes against a section of the outer housing.
 26. A seat assembly, comprising: a seat; a back part; and a support structure according to claim 1, wherein the support part supports at least one of the back part and the seat.
 27. A seat assembly, comprising: a seat; a back part; and a support structure according to claim 1, wherein the support part holds at least one of the back part and the seat in a position, wherein the position is a function of a position of the support part relative to the base support. 